This invention pertains to controlled shear point adapters for mounting and connecting electrical wires and fiber optic cables. More particularly, this invention pertains to a controlled shear point wiring adapter with an anchored bottom segment and a quick release top segment. The wiring adapter is positioned in a control box or other mounting cabinet structure to facilitate the connection of various wires utilized in the structures, such as the power wires from a power source to the control box or the control wires from the control box to external control elements. When a physical stress is placed on the wiring system, the quick release function of the wiring adapter is triggered to separate the top segment from the bottom segment, such that the shear point of the wiring system occurs at the wiring adapter.
The power systems utilized in the control boxes or other mounting cabinet structures will typically require physical wires that provide connectivity to a source of power. The control systems will also have significant wiring requirements to provide connectivity between the control elements in the control boxes and the external control elements and sensors. Fiber optic cables may be used for traffic monitoring and control, as well as road structure monitoring, where communicating information to a traffic management center or other control center via a fiber optic communication system is advantageous. The physical wires and fiber optic cables may be buried in the ground or run behind walls or mounted on poles above ground level. In many situations, it is difficult to access or repair the physical wires in the event that the wires are damaged.
In a control box, stable junction connections between terminals in a power system or control system are preferred. The connection requires that the terminals be properly aligned and held steady during operation in a clean connection. These connections are susceptible to damage caused by sudden motion. Sudden motion may damage the physical wires by pulling, tearing, or breaking the physical wires.
The physical wires are generally made up of a plurality of segments connected together through junctions. In many applications where a junction is use to connect a first terminal is connected to a second terminal, a rigid connection is required. The advantage of a rigid connection is that it promotes the connection between the first terminal and the second terminal with transmission mediums such as electrical signals, power supplies, or fiber optic light waves. The disadvantage of such a connection is that any force applied to the connection may result in damage to the physical cable connected by the junction. In order to avoid damage caused by forces applied to the junction, a quick release mechanism is available to provide the advantages of a physical connection between the first and second terminal while allowing for a quick release of the first terminal from the second terminal in the event of a force being applied to the junction.
For both the outdoor and in-building control box installations, the wires are often placed in conduit or other ducts. The conduit provides protection for both physical and environmental abuse. In underground installations, the conduit protects the cable from shifting rocks, aggressive rodents, digging equipment, and other hazards. In metropolitan areas, multiple conduits are often grouped as duct banks to accommodate future growth of the wiring infrastructure without major traffic disruptions from cutting and trenching of the streets.
Control boxes are used extensively in the transportation industry for various traffic control and road monitoring applications. The control boxes are generally mounted along the edge of the highway or local streets in proximity to the location of the traffic signals or other traffic control or monitoring elements. One of the most expensive problems in operating such systems is to repair damages to the wiring systems caused by traffic accidents which physically damage the control boxes. The wiring connections inside the control boxes are often ripped apart and destroyed. The physical wires, which are in a conduit buried under ground or mounted on a pole, are damaged within the conduit. In such a case, the wiring may need to be re-laid from the source to the destination. The process of replacing wiring connectors and relaying the physical wires is time consuming, labor intensive, expensive, and dangerous. The longer an intersection is disabled for repair work, the more likely it is for secondary accidents to occur.
In order to minimize the damage caused by sudden physical stress to a wire, it is desirable to control the shear point, which is the point at which the wires break when sufficient stress is applied. When the wiring system is stressed, the quick-release function of the wiring adapters ensures that the shear point occurs at the adapter and not elsewhere in the wiring system. By controlling the shear point, damages to the wiring system caused by a physical stress are limited, and the time and expense for repairs are drastically reduced.
Another concern when a control box is damaged in a traffic accident or other incident is an exposed power wire. When the wires are ripped apart in the accident, one end of the wires will still typically be connected to a power source. Although the power source may have an electrical circuit breaker in the system, the circuit breaker may not always trip when the wires are damaged. Any exposed live wires at the scene of the accident may be an electrical hazard to any persons at the scene of the accident. When a stress occurs in the wiring system and the top segment of the wiring adapter is separated from the bottom segment, the exposed ends of the power wires are still retained in the lower adapter segments, thereby reducing the danger caused by exposed wires. The electrical connectors on the lower adapter segment are recessed to prevent accidental human contact.
The control boxes for traffic control and many other applications, such as street light poles, dynamic message boards, school crossing lights, and speed monitoring poles, are mounted outdoors. When torrential rain or snow storms occur, the inside of the control boxes may have standing water, which may damage the wiring systems and create an electrical hazard for persons around the control boxes. The controlled shear point wiring adapter of the present invention is a sealed adapter such that the adapter continues to function when exposed to standing water.
Wiring damages caused by control box accidents are also a concern in industries other than the transportation industry. Control boxes are used in other outdoor and indoor applications where the wires are positioned in underground conduits or other conduit locations where wire repairs would be difficult. For example, street light poles, which typically have underground power wires but no control wires, frequently have damage to the power wires caused by traffic accidents.